In the field of current sources or current sinks an output current can be generated which is controllable by a certain number of bits to tune the exact value of the output current. One existing implementation of such a digitally controlled current source comprises a transistor arrangement for sourcing the output current and a regulation circuit. The transistor arrangement and the regulation circuit are coupled to each other via a set of switches which are directed by a control signal comprising a number of bits. The number of bits determines the number of levels of the digitally controlled source. The number of transistors of the transistor arrangement corresponds to the number of bits. The sizes of the transistors are selected in a way that they increase with 2n, with n ranging from zero to the total number of bits. The regulation circuit generates a constant reference current which is used by the transistor arrangement to source the output current depending on the control signal.
In some applications, a controlled current source with less power consumption can be necessary.